Using NixOS as my daily OS on a X1 since six years now.
The first months have been hard as at this time was no installer at all and I had to do everything manually. After a while I got used to the update process.
Recently I switched to Nix Flakes which is another challenge but seems to make the Nix way even more consequent.
The only odd thing what drives me nerves is that compiling on that machine takes sometimes a half day.